Trucks, such as dump trucks, have commonly been used to convey materials such as salt, cinders, chemicals and/or sand for the purposes of spreading these materials onto road surfaces to improve the traction of the road surface during hazardous conditions. The materials in the truck are commonly dispensed by tilting the dump body of the truck thereby releasing the goods from the dump body and/or conveying the materials within the dump body out through an opening in the rear of the dump body. The materials which are conveyed out through the rear of the dump body can be spread by use of a spinner which creates a wide spray pattern behind the rear of the truck as the truck moves in the forward direction. Such a spinner design is known as a broadcast spinner design and is illustrated in U.S. Pat. Nos. 4,266,731, 3,332,691; and, 3,113,784.
In some applications, it is sometimes desirable to be able to spread the particulate material in a relatively narrow strip in the road. In such circumstances, a broadcast spinner design cannot perform such a function since the spinner sprays the material over a wide area on the ground surface. In order to prevent the broadcast spraying of the particulate material, a material guide must be positioned closely adjacent to the rotating spinner so as to narrow the spread of particulate materials being deposited onto the ground surface. One such material guide is disclosed in U.S. Pat. No. 3,332,691.
The '691 patent discloses a material guide attachment attached and positioned on the side of the spinner. The attachment is adapted to receive materials which are projected toward the side of the truck and to guide the projectory of such materials 90.degree. so that such materials are deposited rearwardly of the direction traveled by the vehicle. The '691 patent also discloses that the material guide attachment is designed to deposit the particulate material at a rearward velocity which is substantially equal to the forward velocity of the vehicle so that the velocity of the particulate material upon contacting the ground surface is substantially zero. The design disclosed in the '691 patent has been found to adequately deposit materials in a narrow strip as long as the truck maintains relatively slow velocity. However, it has been found when the velocity of the truck exceeds 25 mph, the material guide design is unable to maintain rearward velocities of the deposited particulate material to coincide with the forward velocity of the vehicle thus resulting in unwanted bouncing and scattering of the particulate material. This speed limitation is a result of the material guide attachment design. The spinner of the '691 patent propells the particulate material in a direction perpendicular to the forward movement of the truck. The material guide attachment includes a 90.degree. shoulder adapted to redirect the propelled particulate material 90.degree. so as to deposit the particulate material rearwardly of the forward moving truck. Due to the design of the 90.degree. shoulder, the velocity at which the particulate material is directed toward the shoulder has to be minimized so as not to powderize the particulate material upon contact with the shoulder or to cause the particulate material bounce off from the shoulder. As a result, the velocity at which the particulate material could be propelled from the spinner was limited. Furthermore, the impact of the particulate material onto the shoulder of the material guide causes the particulate material to cake and to deposit on and around the shoulder. Such a caking problem is compounded in wet road conditions and/or when deicing fluid comes in contact with the material guide. Since the material guide is not shielded from the environment, caking and corrosion of the material guide can rapidly occur. The caking problem, especially at the shoulder of the material guide, adversely effects the velocity of the particulate material being redirected by the material guide, thus resulting in uneven reward velocities of the particulate material and unwanted scattering of particulate material on the road surface. Consequently, the material guide must be periodically cleaned in order to achieve zero velocity spreading at low forward truck velocities. The material guide of the '691 patent has the added disadvantage of not being able to prevent particulate material from being propelled over the top edge or under the bottom edge of the shoulder which results in the waste of particulate material off the side of the road. Such wasted particulate material was not only costly, but can be adverse to vegetation on the side of the road. In addition, the '691 patent does not disclose a spreader which can deposit the particulate material in a narrow strip irrespective of the velocity variations of the truck during operation.
As a result of the limitations in material particulate spreaders to deposit a particulate material in a substantially narrow strip along the road as the truck travels over a large range of speeds, there has been a demand for a material guide which can overcome such deficiencies. In addition, there is developed a demand for an integrated control system which both controls the rate materials are deposited to the spreader and the velocity to which the spreader ejects particulate materials to obtain the desired quantity of particulate material spread on the ground in a desired spread configuration.